On Tue, Nov 11 2014 at 7:37pm -0500, Josef Bacik <jbacik@xxxxxx> wrote: > Hello, > > I'm creating a dm target to better test power fail situations and > I'm having trouble figuring out how to make the dm device appear as > a different size. So for example you do the normal dm table > > offset size power-fail /dev/whatever args So "size" should be constrained to: size=$(sudo blockdev --getsz /dev/whatever); $((size/2)) > I want to use the entire size of /dev/whatever, but I want my dm > device to show up as size/2. So right now I'm doing this in my > ->ctr function > > ti->len /= 2; You don't want to mess with ti->len. If you have "size" be size/2 then ti->len will automatically reflect that. But anyway, I'm mot really following how you'd map the entire /dev/whatever but only expose half its size to the user. What would the target's ->map function be doing? > Is that acceptable, or will this have some side-effect that's going > to bite me in the ass? I can't see any other target that does > something similar and there appears to be no helper function. This > seems to work as far as blockdev --getsz is concerned, but I'm > worried I need to do more. Thanks, dm-thinp is all about establishing thin volumes of fictional size... wondering what kind of helper you were hoping to find. The target's ->ctr would open /dev/whatever and internalize /dev/whatever's size and ->map would deal with remapping of bios sent to the target over to /dev/whatever. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
